The present invention relates a label machine for in-mold labeling of plastic bottles having a circular cross-section configuration, a major portion of which defines a cylinder. In-mold labeling refers to a processes and apparatus for affixing labels to articles such as plastic bottles during the molding process by inserting labels in the recess of a mold section, closing a pair of mold sections around a length of heated, plasticized tubing and expanding such tubing into conformity with the mold cavity defined by the recesses of the closed mold sections thereby causing the label to become affixed to the wall of the newly blown bottle.
The prior art discloses many types of methods and apparatus for accomplishing in-mold labeling of plastic bottles. For example, U.S. Pat. No. 5,350,483, which is incorporated herein by reference, discloses an in-mold labeling insertion apparatus and method according to which there is provided a carriage carrying at least one label holder. The carriage is moved in unison with the mold along a parallel path with the face of the open mold section. The carriage has a label inserting beam extending forwardly therefrom and a label holder operable to (1) receive a label from a label magazine and (2) release the label on the wall of the recess of one of the mold sections upon advancement of the carriage and insertion of the beam and label holder thereon between said open mold sections. Other methods and apparatus for in-mold labeling are shown in U.S. Pat. Nos. 4,639,206; 4,355,967; 4,479,770 and 4,479,771.
In the blow molding of plastic bottles, it is desirable to utilize blow molds having a plurality of molding cavities so that a plurality of bottles are molded in each molding cycle of a set of blow molds. The blow molds utilize first and second sections which open and close. Recesses are formed in the mating faces of each of the mold sections. When the mold sections are closed, the recesses cooperate to define cavities in which the bottles are blown. Heretofore there has not been widespread use of in-mold labeling for bottles having a cylindrical body portion, particularly in those situations where it is desired that substantially the entire circumference of the bottle be encircled by labels from the mating mold sections. In order to affix labels which substantially encircle the entire circumference of a cylindrical portion of a bottle, each mold section should have inserted in its mold recess a label having a length equal to the circumferential wall portion of such mold recess. Since two mold sections are normally utilized in blow molding a plastic bottle, the circumferential length of the cylindrical portion of a recess of each mold section will be equal to one-half of the circumference of the cylindrical portion of the bottle being formed. Accordingly, the length of a label to be inserted in each mold section recess will be equal to or substantially equal to one-half of such bottle cylindrical portion circumference.
As mentioned previously, it is frequently desirable to utilize blow molds having a plurality of molding cavities aligned with one another with a single tubular parison being blown in each such molding cavity simultaneously with other parisons being blown in their respective cavities while the mold sections are closed therearound. Depending upon the size of the bottles being blown and the type of machine, there may be 2, 4, 6 or even 8 aligned bottles being blown simultaneously. In order to minimize the space occupied by the blow molding machine, it is desirable that each of the cavities be positioned as close to the adjacent cavities as feasible. Such close positioning of the cavities will also minimize the amount of metal required to be utilized in the molds and related equipment and minimize the amount of energy required (1) to move the mold sections between open and closed positions and, (2) depending upon the type of blow molding machine, to move the mold sections laterally from a position beneath an extrusion die orifice for receiving a plurality of tubular parisons to a position at which air is introduced therein to expand the parisons in their respective mold cavities. However, the closeness of the positioning of adjacent mold cavities results in the distance between adjacent mold cavities being significantly less than the length of a label having a length equal to one-half the circumference of the cylindrical portion of bottle being molded. It should be noted that the labels are substantially flat or planar when they are removed from a label magazine by a label transfer mechanism which transfers the labels from the label magazine to the mold recesses. As a result of the length of such labels, when flat, being greater than the distance between adjacent mold cavities, it is necessary that the labels being carried by adjacent transfer mechanisms have overlapping edges. As well be appreciated, such lengths of the labels in relation to the spacing between the mold cavities does not permit the simultaneous utilization of separate label magazines aligned with each mold recess.
Under the present invention, a label dispensing magazine having multiple lanes for dispensing labels is provided with a magazine shuttle to shuttle the labels and magazines from a first position aligned with one vacuum label holding head to a second position aligned with an adjacent vacuum label holding head. Assuming that the mold has four sets of mold cavities and the label magazine has two dispensing lanes, the magazine shuttle moves the magazines from a position at which the first and second dispensing lanes of labels are aligned, respectively, with the first and third vacuum label holding head. After t he first an d third vacuum label holding heads remove labels from the first and second dispensing lanes, the magazine shuttle is actuated to move the label magazines to a position such that the first dispensing lane is aligned with the second vacuum label holding head and the second dispensing lane is aligned with the fourth vacuum label holder. The vacuum label holding heads may then be moved into alignment with the respective mold recesses and moved into the recesses to deposit the labels simultaneously in each such recess. The labels supported on adjacent vacuum label holding heads will have overlapped edges with the adjacent labels; however, this does not interfere with the placement by the vacuum label holding heads of their respective labels into the adjacent recesses.